US2017305A - Process of hardening cams - Google Patents

Description

Oct. l5, 1935. D. J. CAMPBELL 2,017,305

PRocEss oF HARDENI'NG CAMS Filed Juned 19. 1955 s sheets-sheet 1 Q l Dona@ c). Campbe @brug Q Oct. l5, 1935. D. J. CAMPBELL 2,017,305

PROCESS OF HARDENING CAMS Filed June 19, 1933 5 sheets-sneet` 2 CIC. 15, 1935. D. J. CAMPBELL 2,017,305

PROCESS OF' HARDENING CAMS Filed June 19, 1933 3 Sheets-Sheet 5 Aovxla s Patented Oct. 15, 1935 UNITED sTATEs PATENT ol-FlcE PROCESS F HABDENING CAMS ,Application :uns 19, 193s, semi No. 676,461

1 clam. (ci. 11s-1o) This invention relates to a process of hardening and is made use of particularly in hardening cams on cam shafts which are cast integrally with the shaft from a' suitable composition cast iron.

s Cam shafts, in conjunction with cams thereon,

are used in internal combustion engines for operating the valves; and these cams are subject to severe wear and must be of a. hard and durable character. Previously, cam shafts have been largely made of a suitable grade of steel, forged to shape, and thereafter subjected to a hardening operation which hardensv only the surface of the cams.` This-hardening operation, involving as it does the use of high degrees of temi perature.' is not only rather long and costly, but the shafts are subjected to danger of warping with a resultant loss of complete forged and heattreated shafts, thus resulting in high cost of production. It has 'also been contemplated that-the cams on cast -iron cam shafts might be hardened in the operation of casting by placing chills in the mold against whichthe iron of the cams would come when themold was poured to cast the shaft. This has proven quite successful. The

2l time and labor consumed in setting the chills in the mold is an item of expense, however, slowying down'production and increasing molding costs which the present invention eliminates.

In the present invention the cams, which are cast integrally with the shaft, are each successively heated in a manner to rapidly raise the temperature of the cams to a degree sumciently high to combine a high percentage of the carf bon therein and then cooling the heated cam with 'a greater or less degree of rapidity in accordance with the degree of hardness desired. portion of the cam to be hardened is heated to substantially a red color, or above its critical point, and is then released from the heating apparatus and is either subjected directly to the cool atmosphere, which causes the cam to rapidly cool, or air at a lower degree of temperature than the'atmosphere, or even at atmospheric tempera; ture, may be blown over the cam and shaft to, more rapidly cool the same, producing a hard an an exceedingly durable, wear resisting cam strucr ture. After the cams on a shaft have been thus heat treated or hardened, the cams are finished by a grinding operation.

An understanding of the invention may b hadV from the following description, takenin connection with theaccoinpanying drawings, in which,

Figure 1v is a. plan view of a machine for carrying out the cam hardening process of my ini vention.

Figure 2 is a front elevation thereof.

Figure 3 is an end view at the left-hand end of Figure 2. f

Fig. 4 and Fig. 5 are transverse sections `through the machine illustrating the cam holding heating electrodes in their operative and released positions, respectively.

Fig. 6 is a fragmentary longitudinal verticalsection through one 'end o'f the cam shaft holder located at the left-hand end ofthe machine. i0'

Fig. 7 is a transverse vertical section through the carriage which carries the cam holding and heating electrodes, and

Fig. 8 is an enlargedelevation illustrating the manner in which each cam is subjected to heatl5 ing electrically to raise the temperature thereof.

Fig. 9 is an enlarged .elevation illustrating the manner lin which the cam is subjected to heat.- ing electrically when the electric current is passed from side to side of the cam and not through the shaft.

" Like reference characters refer to like in the diiIerent gures of the drawings.

A- description of the preferred construction and operation cf the machine shown in the drawings will disclose the manner in which the process is performed. In construction, an elongated supporting bed I, at its upperiside is equipped with guide and holding plates 2 bolted in place and lying lengthwise or tile bed at born the from; $0 and rear of the upperQ side thereof. At one end of this bed a' fixture is secured comprising a post 3 which has a base with edge portions extending underneath the holding plates 2, at the upper end or which is a sleeve l. At the other end of That the elongatedsupport i a carrying member 5 is adjustably secured whereby the same may be adjusted to different positions along the bed l by releasing the plates 2, shifting .the member i to a desired position andthen tightening the bolts o to hold it securely in place. 0n this member 5 a support '6 is slidably mounted which at its upper end, is equipped with a sleeve 1 similar in substantially all respects to the sleeve 4 at the upper end of the support 3. The movement -if-45 the slidable support 6 lengthwise of the member 5 is controlled by va lever 8 pivotally mounted at one end of the part 5 and extending through an opening in the lower portion lof the support 6, the free end of the lever 8 extending in front of 50 the machine so that the operator thereof may engage the same with his hipv and by moving -sidewise carry' the support 6 with the connected 'sleeve 'I and the parts mounted thereomto the left (Figs. 1 and 2). Normally this free slidable u support I will be moved inwardly toward the right, there being connected therewith a bar 8 to which one end of a heavy coiled tension spring I8 is secured the other end thereof being secured to the part 5, whereby on turning the lever 8 to the left spring Il is stretched.

At the inner ends of both of the sleeves 4 and 1 a chuck Ii is mounted, each of which at its inner end is provided with a tapering bore I2, one of said portions I2, namely, the one at the left hand end of the machine, being knurled as shown in Fig. 6. The chucks II are rotatably mounted on the respective inner ends of the sleeves 4 and 1, suitable anti-friction bearings I3 being disposed between each chuck and its carrying sleeve; and the sleeve 4 at the left-hand end of the machine is provided with a collar lia in -which radial openings spaced from each other are made for the reception of a rod to manually turn the chuck ii, as is evident.

A rod i4 is slidably mounted lengthwise of the sleeve 1 and is normally pressed inwardly by a coiled spring I8 as shown in Fig. 6, the inner end thereof being adapted to contact with an end of a cam shaft located in the chuck. An electric conduit I6 is connected to the outer end of the rod I4 of the xture at the left-hand end of the machine.

It is apparent that a camshaft I1, on which there are located in spaced apart relation a plurality of cams i 8, may be disposed between the two holding chucks II by operating the lever 8 to the left placing the camshaft in position and then releasing the lever. The reduced end portions I1a of the cam shaft I1 engage with the ends of the contact rods I4. And from the rod I4, which extends lengthwise of the sleeve 4, an electric cable I8 may lead, as shown.

A rack 20, having rack teeth at its upper side,

is located lengthwise of the bed I and substantially centrally thereof. Over this a supporting carriage is mounted including a nat plate 2i which slides underneath the retaining guide plates 2 and upon the upper side of the bed I. Integral with the plate 2i is a housing 22 in which a pinion 23 is housed, meshing with the rack 2li and having a shaft 24 which extends outwardly to the front side of the machine, and is equipped with a wheel 25 to turn the pinion and thereby move the carriage and attached parts to different positions in the length of the machine.

The carriage also includes two upwardly extending and spaced vertical supporting posts 26 and 21. A lever 28 is located between the posts toward their lower ends and pivotally mounted thereon, the forward end carrying an electrode 29, preferably of copper, connected with which is an electric conduit 30. The lever `28 is pivotally mounted between its ends on the posts 2 8 and 21 at 3i.

At the upper ends of the posts 26 and 21 and between the same is a second lever 32, pivotally mounted between its ends at 33, and at its front end and on the underside thereof carrying an electrode 34 preferably of copper which is insulated from the lever 32, on which it is mounted, by suitable insulation 35.

An operating handle 38 is pivotally mounted at its lower end on the rear end of the lever 28. A link 31, adjustable as to length is pivotally connected at one end to the operating handle 3B a short distance above the rear end of lever 28 and at its other end has pivotal connection with' the rear end of the lever 32, whereby on pulling the handle 36 to a vertical position, as in Fig. 4,

l:torneos the two electrodes 34 and 29 are brought toward each other and may clamp a cam shaft and a cam thereon between them as shown; and on throwing the operating handle 3B backward to the position shown in Fig. 5, the electrodes 28 5 and 29 are moved away from the cam shaft I1 releasing the same. An electric cable 38 c0nnects with the electrode 34 as shown in Fig. 2.

In operation, after a cam shaft has 'been placed between the holding chucks II, the wheel 25 is l0 moved so as to bring the electrodes 29 and 34 opposite the selected cam' I8 to be treated. In practice the hardening process will ordinarily begin at the cam nearest one end of the shaft, and will then be performed successively upon the 15 cams until the one nearest the other end of the shaft is finished. The knurled character of the chuck at the left end of the machine causes the shaft to turn with such chuck, and by inserting a rod in an opening in the annular flange lia 20 the cam shaft may be turned such that the cam selected for the hardening process is positioned towards the electrodes from the shaft, whereby on moving the operating handle 3B from the position shown in Fig. 5 to that shown in Fig. 4 25 the opposite sides of the cam I8 bear against the inner inclined sides of the jaws at the lower end of the electrode 34 as best shown in Fig. 8; while the lower arc-shaped side of the cam I8 bears against the upper side of the electrode or 30 anvil 29.

When the electrodes thus contact with and clamp against a cam I8 on the shaft electric current is passed through the cam and serves to rapidly raise the temperature of the cam to a 35,

temperature above the critical or approximating I000 F. or more. The operator can judge by the color which is produced when approximately the desired temperature has been reached.

The operating handle 36 is then turned tothe 40;

position shown in Fig. 5 thus automatically stopping electric current iiow and releasing the cam.

.Upon the cam being released, which has been heated, either the direct lower temperature of the surrounding atmosphere will act to rapidly 45,;

lower the temperature, or air may be blown upon the cam to more rapidly lower the temperature. For succeeding cams the operation is repeated. Upon releasing the electrodes from a selected cam, the wheel 25 is moved to bring the electrodes to the next adjacent cam, the shaft is turned by turning the chuck II at the left-hand end of the machine to properly position the` cam which is to be heated, andy then the lever 36 is moved from the position shown in Fig. 5 to that 55;

shown in Fig. 4. 'Ihe treatment of all of the cams on a cam shaft is very rapid and in a camshaft having ten cams, as shown in Fig. 1, the entire heating of all of the cams does not necessarily consume over thirty seconds.

The degree of hardness of the cams may be controlled by the rapidity with which the temperature of the cams is raised and the rapidity with which the temperature is reduced after electric heating. It may be reduced, as said before, by blowing cold air on them or cooled by a desired. temperature water or other fluid.

The process described is rapid, efficient and economical. The cams are cast in the first instance, together with the shaft, as iron castings, cleaned of sand and loose scale, taken to the machine which is used to electrically heat the same, raised to a high degree of temperature, approximating 1000 F. or more, and then cooled rapidly, it being understood that the rate of heatai Bil lng and cooling may be controlled and the' faster I claim:

the heating and the faster the cooling takes place, vThe process of heat treating a cast iron cam the harder the cams will be; likewise, the higher shaft which consists in separately heating the the temperature, the harder they will be. cams on said cam shaft by passing electricity 5 While I have described my invention as carried through the cams in two paths so as to symmet- 5 out with an electrical heatingapparatus, I wish rically heat the cams, said path starting near it understood that the heating apparatus is not the highest point of the cam but on opposite a part of this invention and that any method sides thereof, and then cooling the cams. of heating the cams can be employed without 10 departing from the invention. x DONALD J. CAMPBELL. 10

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